// Copyright (c) 2018, Yubico AB
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package com.yubico.webauthn.attestation.resolver;

import com.yubico.internal.util.CollectionUtil;
import com.yubico.webauthn.attestation.TrustResolver;
import java.security.cert.X509Certificate;
import java.util.List;
import java.util.Optional;

/**
 * A {@link TrustResolver} whose {@link #resolveTrustAnchor(X509Certificate, List)} method calls
 * {@link TrustResolver#resolveTrustAnchor(X509Certificate, List)} on each of the subordinate {@link
 * TrustResolver}s in turn, and returns the first non-<code>null</code> result.
 */
public final class CompositeTrustResolver implements TrustResolver {

  private final List<TrustResolver> resolvers;

  public CompositeTrustResolver(List<TrustResolver> resolvers) {
    this.resolvers = CollectionUtil.immutableList(resolvers);
  }

  @Override
  public Optional<X509Certificate> resolveTrustAnchor(
      X509Certificate attestationCertificate, List<X509Certificate> certificateChain) {
    for (TrustResolver resolver : resolvers) {
      Optional<X509Certificate> result =
          resolver.resolveTrustAnchor(attestationCertificate, certificateChain);
      if (result.isPresent()) {
        return result;
      }
    }
    return Optional.empty();
  }
}
